K77 round vs square magnet?

[Rotorhead09]

Can anyone tell me the diffrence in the K77 tweeter with the round magnet vs the square magnet? Any diffrence in performance? I'm sure this has been asked before. Just can't find anything on the forum on it.

Thanks in advance!

Santa Lee

[JohnA]

The round magnet K-77 has a power rating of 2 watts continuous/20 watts

program vs 5/50 for the K-77-M. The -M has a little more output

above 10k and is slightly smoother.

A K-77 can be uprated to the -M's level with a diaphragm change, but there are no more 16 ohm diaphragms available.

If you want your rebuilt, You can do it your self, or have Bob Crites do it. Bob can sell you the parts, too.

[DizRotus]

The round Alnico magnet K-77 (EV T-35) is older and has a mystique that might not be merited by the differences. The newer square magnet K-77M (M stands for mud) has a ceramic magnet and is generally slightly more efficient (higher sensitivity), i.e., louder.

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Bob Crites, whose opinion I hold in high regard, strongly favors the Alnico version over the mud magnet. Some have said that the Alnico magnets can become de-magnetized over time, however, its my understanding that Bob Crites has tested MANY and never observed that to be the case.

Some people prefer one and some prefer the other. Each can be fitted with either 8 ohm or 16 ohm diaphragms.

[Rotorhead09]

Hey guys,

Thanks for the info. I just run across some tweeters this guy (local) had and he had one of each. I just wanted to know the diffrence. Though about picking them up.

Santa Lee

[Guest " "]

I'll post some manufactures technical data for both the round magnet and square magnet version tonight when I get home.

But in terms of performance (how do they sound), heres my ranking. Im going to include anything I have that has the same voice coil.... best sounding to me first...least liked last.... I have not tried Bob's new horn yet and I don't have one of the t-35s with the small slotted half size looking horns.

a. ev t-350, best sounding use of the t-35 diaphragm, extremely large magnet, extremely large horn, close to the same depth, will not fit with out modification in place of a t-35 or k-77. specs say 23,000hz for the diaphragm when used in this unit. the parts are not interchangeable with any other t-35 or k-77

b. ev st-350 A or B, this has both a hidden round magnet underneath a round magnet cover and a flat square magnet not covered. magnet is larger than any used on a t-35 or k-77, horn is a wide high dispersion type that sounds awesome, specs say the diaphragm when used in this horn can go done to 3000 hz...horn is a little deeper than the other implementations, interestingly, will not fit with out modification in place of a k-77 or t-35, but interestingly parts are interchangeable, you can mount an st-350 a or b magnet to a t-35 or k-77 horn.

c. ev t-35 round magnet, flat cap on the magnet, magnet assembly is usually white or gray in color, often mounted to a chrome horn. 8 ohms, specs say 18000hz, which is higher than the specs for the below t-35 or k-77's

d. ev t-35 round magnet, flat cap on the magnet, magnet assembly is usually black, mounted to a black horn. 16 ohms

e. ev t-35 also labeled k-77 and speakerlab labels as ht3500 and I think I saw a mcintosh branded one as well. round magnet cap, mangnet assembly is bronze looking (I think this is brush caadium plating), mounted to a black horn, 8 or 16 ohms. I also have a black painted set mounted to a chrome horn.

f. k-77-m, square magnet, spaded solder terminals, this version as a round plastic sticker on the face of the magnet exposed to the voice coil diaphragm (I guess an attempt to soften the sound), mounted to a black horn

g. ev t-35A , square magnet, push-pin terminals, black horn, no sticker on magnet face (sounds brighter than the k-77-m)

h. k-77-f, square magnet, spaded solder terminals, black horn, and sounds like the k-77-m

i. tw-35, round magnet, usually painted grey, attached to a grey horn, magnet is smaller than the other round magnet t-35's or k-77's.

If anyone sees any errors or omissions...by all means jump in.

[Trey Cannon]

The round Alnico magnet K-77 (EV T-35) is older and has a mystique that might not be merited by the differences. The newer square magnet K-77M (M stands for mud) has a ceramic magnet and is generally slightly more efficient (higher sensitivity), i.e., louder.

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Bob Crites, whose opinion I hold in high regard, strongly favors the Alnico version over the mud magnet. Some have said that the Alnico magnets can become de-magnetized over time, however, its my understanding that Bob Crites has tested MANY and never observed that to be the case.

Some people prefer one and some prefer the other. Each can be fitted with either 8 ohm or 16 ohm diaphragms.

Then he has not tested enough of them...They do loose their magnet strigneth over time.

[Deang]

So, what would be the impact -- a reduction in sensitivity, bandwidth, or both?

[Guest " "]

does anyone have an alinco magnet k-77 or t-35 that failed the magnetic feild test?

what method of test was used?

[Trey Cannon]

Sensitivity for the most part.

I have been told that they can be re-charged.

I have not tried that. If you have ever seen a magnet charger chunk a unit across the room you would undrestand why.

it is more save to buy a new unit.

[Malcolm]

You can get an indirect idea by measuring sensitivity. To find out the true exent of demagnetization you would have to measure with a gaussmeter and compare the result to the original strength. You have to place the probe of the gauss meter in the gap. Not a problem for a K77 because the diaphragm is easily replaceable. More of a problem for a woofer. And of course, you need to know the original strength.

[colterphoto1]

EDIT

ok, I'm stupid, but didn't the last letter usually stand for the manufacturer of the speaker? Did M really stand for 'mud'? or something else?

[RAD]

The way I understand it the k77m was in fact made by Electro-voice. The new k77f is made in the Philippines but I have no idea who the manufacturer is.

[DizRotus]

Michael-<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

I believe you're confused about the K-77s, all varieties of which were built by EV until they stopped producing the T-35 in its various incarnations. Klipsch then had T-35 clones made in the <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Philippines as the K-77F.

[Trey Cannon]

M = mud

EV did build all the 77's until about 2001. After that a US vendor bought the tools and started production in the Philippines. After about 9 months to a year later they got it right. Thus we have the "F".

They only good thing about that is all the Dia. fit all the motors.

If you have a "77" the "F" dia. will fit.

[Coytee]

b. ev st-350 A or B, this has both a hidden round magnet underneath a round magnet cover and a flat square magnet not covered. magnet is larger than any used on a t-35 or k-77, horn is a wide high dispersion type that sounds awesome, specs say the diaphragm when used in this horn can go done to 3000 hz...horn is a little deeper than the other implementations, interestingly, will not fit with out modification in place of a k-77 or t-35, but interestingly parts are interchangeable, you can mount an st-350 a or b magnet to a t-35 or k-77 horn.

Hello from (non sunny) San Diego!! whoo hoo... start our trek back to Tennessee in couple days.

Speakerfritz, I'm curious if you have any familiarity and thought comparisons between the EV ST 350 and the JBL 2404. Reason I ask is I happen to have a pair of the ST 350's (mounted in their respective speakers) and a pair of the 2404's. I was told the JBL's would take the EV's apart so I bought a pair.

Don't know that I care to steal the 350's out of their current home so just looking for your thoughts, if you have any, regarding the two. Perhaps if you have a strong enough opinion, I might yank them out of their home and do more investigating.

[Guest " "]

My take...I have listened to the JBL 2404 and their clones...awesome sound....but I never directly compared to the t-350.....to speculate...I didn't include in my hit parade only because it does not use the same coil as the ones I mentioned.

if you are using an extreme slope network...I think since it is a bi-radial with its 100x100 degree pattern, it will have a wider dispersion than the t-350. The sense of excitement can be compared to current fourm members who are evaluating the 511b horn vs the k-400/k-401, etc. Less beaming...great imaging...high detail.

But if you are using a gentle slope network....the overlap at high volumes may be colored.

the min recomened cutoff for the 2404 is 3000hz at 18 db per octave. The AA or A nerwork is not an 18 db per octave network. consequently if you use the A or AA...there will be overlap into lower frequencies.

the frequency response of the jbl 2404 is +- 3db from 4k thru 19k but when used between 3k - 21.5 k it broadens to +- 10 db.

so in summary if you upgraded to an extreme slope network and are cutting off at least at 4k, I think you will be very pleased with the results. but if you are using an A or AA, results will be mixed depending on if you are a low volume or high volume listener.

2404.pdf

[Deang]

Trey, I was told the letter at the end was the vendor code: V=Altas, M=Electrovoice, E=Eminence, K=Klipsch, H=Hepner. Looks like the vendor codes, at least for the tweeters and mids, were tied to the magnetic material.

I also thought the early K-77s were made by University.

[Guest " "]

I seen this document before...I have the exact same document...same photo...same spec's...in a data sheet that came with a pair of EV t-35A's....the data sheet I have is letterheaded electro-voice rather than univeristy. my ev t-35a's are push-pin type rather than the terminal spade type used in the k-77--m or k-77-f's

[Guest " "]

I seen this document before...I have the exact same document...same photo...same spec's...in a data sheet that came with a pair of EV t-35A's....the data sheet I have is letterheaded electro-voice rather than univeristy. my ev t-35a's are push-pin type rather than the terminal spade type used in the k-77--m or k-77-f's

[BEC]

Dean,

I think the latest K-77Ms were made by University after University became part of Electrovoice. I had lots of new T-35As a few years ago that I was selling and they were all marked University Sound.

Don't forget the K-51V ceramic and the K-55X alnico both made by Atlas when trying to figure out vender codes.

Also the woofer code seems to indicate city of manufacturer.

K-33E Eminence, KY

K-33P Paducah, KY

K-33B Brownsville, TX

Bob Crites